has tried Mame_libretro Core (Mame 0.187) works very well but it seems that the digital inputs (D-Pad / Arcade Stick) is not mapped and only the analog-stick works.
Other Cores i tried (Mame2003, Mame2014, Mame2016) are mapped correctly to digital inputs as standard.
Is this a bug ?
Some of the buttons setting are wrong. But those can be remap from the MAME controller settings.
Right stick does have a problem on mapping though. I think that is broken. 0.187 and 0.188 that I used so far. Never couldn’t get the right stick to map right. I had to use the buttons instead of the right stick to play Robotron: 2084.